This is sort of the tutorials that doesn't make any sense if you are not already knowledgeable in the subject of math and shaders and rendering basics. At first

This is sort of the tutorials that doesn't make any sense if you are not already knowledgeable in the subject of math and shaders and rendering basics. At first I was hopeful that it would finally walk me though the basics of a renderer and explain the concepts behind it, but I was let down :) I have so many questions regardless :) The struggle of a rookie goes as: SECTION A - why on earth do you take the square root of c? Is there a sane reason to do this? SECTION B - why normalize the vector? I'd love to see a detailed explanation. - why is vPos.xy the first two parameters? - is vPos.xy a constant value or is it evaluating as the shader script is executed pixel by pixel? SECTION D - V -= S.xyz; // what's going on here? Why use the -= operator? Is this something to do with the way shaders operate? - float B = 2. * dot(V, W); // what take the dot product? - float C = dot(V, V) - S.w * S.w; // Why take it again and substract a square? - return BB < 4. C ? 0. : 1.; // Why 4.? No other value seems to work SECTION E - "Improve raytrace to return distances of near and far roots." OK I admit that I'm totally lost at this point. Asking line-by-line explanation doesn't really help :) SECTION H - YAY, sin and cos!!! Finally I can mess around with something :)